Fan blade



Dec. 21, 1948. A. KERN 2,456,710

FAN BLADE Filed July 12, 1944 [21 z'm for 15/2 draw firzz,

I I a Attom eys Patented Dec. 21, 1948 UNITED STATES i' y FAN BLADE. Andrew Kern,- Orofinog Idaho Application July 12, 1944,. Serial No. 544,538.

2 Clailns. (Cl. 1 70-135 This inevntion relates to bladesfor fans and more particularly to bladesfor power driven rotating fans.

A primary object of this invention is the provision of an improved type rotating fan embodying a blade of novel construction so designed as to provide an increased flow of air from the fan.

An additional object is the provision of such a device whereby the air is directed in a relatively concentrated flowing cylindrical column from the blades of the fan.

An additional object is the provision of an improved fan blade adapted to contact the air to be propelled therefrom, at the point of initial contact with a relatively low pitch, the blade being so constructed that at its rearmost portion it contains the air at a relatively high pitch.

A still further object resides in the provision of a fan blade which may be attached to the drive shaft of the fan along a line of substantial length whereby to insure a relatively strong joint therewith.

A still further object is the provision of a fan blade which, due to the aforesaid connection, may be made of relatively light thin material.

A still further object resides in the provision of a fan blade of improved efliciency due to its novel configuration,

Other objects reside in the arrangements of material and detailed features of construction, all as will be more fully pointed out hereinafter and shown in the accompanying drawing wherein there is disclosed a preferred embodiment of this inventive concept.

In the drawing:

Figure l is a side elevational view of one blade of a fan constructed in accordance with this invention, and

Figure 2 is a top elevational view of the structure shown in Figure 1.

Like reference characters refer to like parts throughout the several views of the drawings.

Having reference now to the drawings the blank, generally indicated at IU, shown in dotted lines in Figure 1, from which the blade is formed, is generally quadrilateral in configuration. and terminates in four corners l2, l3, I4 and IS. The angles I3-l2--l4 and l2--I4-I5 are preferably right angles, while the angle I3-- i5-M is acute, and the angle I5-I3-l2 is obtuse. Thus the sides 12-43, and I l-l5 are parallel to each other, side I4-l'5 being slightly longer, and form substantially straight lines. Side i2-l4 is also substantially straight and disposed at right angles to the parallel sides above mentioned, and substantially equal in length to side I 2 -13".

Informing a fan blade, generally indicated? at Illa, from blank Hi; corner l5 is curve-r forwardly in the direction of corner I2 substantially about the diagonal between corners l3 and 14, until its apex lies in a plane substantially parallel to the plane formed by the intersection of sides I2-|3 and |2l4, and the distance along the diagonal l2-I 5 is substantially equal to the length of sides 12-83 and |2-M, the extra lengths of sides l3-I5 and Ml5, providing sufficient material to allow for the curvature of the blade from the theoretical diagonal between corners I: and I5.

In forming a fan comprised of blade 10a, two or more of these blades are secured to a suitable driven shaft [6 driven from a suitable power source, as from a motor positioned on the shaft in the direction indicated by the arrow and the letter M, the shaft being rotated in the direction indicated by the curved arrow.

If desired leading edge I2l4 and edge l2--|3 may be reinforced as by the securing of suitable reinforcing strips H and I8, respectively, thereto.

It will thus be seen that edge l2-l4, comprising the leading edge of the fan blade first contacts the air at a relatively low pitch and the trailing edge l i-l5 -I3 strikes the air at an angle at a relatively high pitch, thus insuring a relatively high turbulence of the air contacted thereby.

From the foregoing it will now be seen that the fan blade herein disclosed accomplishes all the objects of this invention and others including many advantages of great practical utility, including among others the fact that the blade may be made of relatively thin and comparatively weak material with no danger of the same breaking at the point at which the blade is joined to the drive shaft due to the relatively great area of juncture of these two parts.

As many embodiments may be made of this inventive concept and as many modifications may be made in the embodiment hereinbefore set forth and disclosed in the accompanying drawing, it is to be understood that all matter herein is to be interpreted merely as illustrative and not in a limiting sense.

I claim:

1. A rotating fan structure comprising a rotating drive shaft, a plurality of curved fan blades each secured longitudinally along said shaft; each blade having been formed from a blank of substantially quadrilateral shape and having two straight edges of equal length at right angles to each other, one of said edges being secured lengthways of the drive shaft and the other forming the leading edge projecting radially from the shaft; the angle formed at the apex between the remaining two sides being less than 90 and the said apex and associated portion of the blade having a curvature resulting in locating the said apex a linear distance from the angle opposite said apex substantially equal to the length of the diagonal formed by taking the square root of the sum of the squares of the said sides of equal length.

2. A rotating fan structure comprising a ro'tat- I ing drive shaft, a plurality of curved fan blades each secured longitudinally along said shaft; each blade having been formed from a blank of substantially quadrilateral shape and having two straight edges of equal length at rig-ht angles to each other, one of said edges being secured;

lengthways of the drive shaft and the other forming the leading edge projecting radially from the shaft; the angle formed at the apex betweenthe REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number i Name Date 1,002,833 Giddings Sept. 12, 1911 2,004,516 Hagen June 11, 1935 FOREIGN PATENTS Number Country Date 5,525 Great Britain Mar. 8, 1909 

